- nearly identical in appearance to the house fly
- dull gray color
- four dark stripes behind head
- tuft of bristles at the base of the calypter
- lay eggs in fresh undisturbed cow manure
- seek indoor overwintering sites in late August – early September
- larvae: cow manure
- adults: watery secretions around eyes, nose and mouth of cattle; flower nectar
- come from farm/ranch areas with fresh cow manure
- congregate on south/southwest- facing walls in late summer – early fall
- large numbers will congregate within wall voids during winter (similar to cluster flies)
- frequently seen in windowsills and light fixtures during unseasonably warm days during winter
- Verify identification to determine appropriate management.
- Seal exterior building cracks throughout summer in areas where flies have been problematic in previous years.
- Tolerate occasional face flies during overwintering months; use a fly swatter; vacuum.
- Search for overwintering flies in voids and mezzanines and vacuum them.
- Use an appropriately labeled insecticidal dust in voids and cracks and crevices where flies overwinter.